Reply by JohnChung

I would say push is not desirable due to the strain on the thumbs. The card scraper should be hard in this case. Most cases a card scraper is sharpen and a burr is created on the edge for shavings. When there is a burr then shavings is created through pushing it.

I started carpentry through scrapers. It was used to remove old lacquer. Much cheaper than sandpaper and more efficient.